Fire damper frames

ABSTRACT

A fire damper frame of folded one piece construction having a centrally open transverse cross section formed from a unitary blank having cooperable interlocking means adjacent opposite ends for rigidly securing the fire damper frame in folded condition. The blank, in unfolded form, has a main planar central web portion disposed between parallel, longitudinally extending side peripheral mounting regions of substantially double blank thickness, and a pair of longitudinally extending, spaced, parallel upstanding flanges disposed at substantially right angles from an inner surface of the main planar central web portion and terminating at longitudinally extending outer edges. Each flange includes longitudinally spaced relief regions defining separate flange sections, each relief region in one flange being in transverse alignment with a corresponding region in the other flange. Each relief region comprises a slit extending from the outer edge of its respective flange in an inward direction for substantially the entire outward extent of the flange, and a portion of at least one of the flange sections adjacent each slit is disposed transversely out of the general plane of the longitudinally extending flange. Adjacent flange sections of each respective flange overlap to form frame corners when the frame is folded through the relief regions transverse to the elongate dimension of the blank to form a substantially continuous peripherally extending channel.

llite States Patent [1 1 1 Get. 30, 1973 [75] lnventor:

[ "FIRE DAMPER FRAMES John C. Kurz, Philadelphia, Pa.

[73] Assignee: Advanced Air Inc., Philadelphia,

[221 Filed: Aug. 20, 1971 1211 Appl. No.: 173,596

[52] US. Cl 52/658, 52/1, 160/381 [51] int. Cl. F2 31 13/10 [58] Fieldof Search 160/381;

287/189.36 D, 20.92 J, 20.92 H, 20.92 D, 189.36 H; 52/317, 475,656, 631,658

Cabral 160/381 x Primary Examiner-Frank L. Abbott AssistantExaminer-Carl D.. Friedman Attorney-Karl L. Spivak ABSTRACT A firedamper frame of folded one piece construction having a centrally opentransverse 'cross section formed from a unitary blank having cooperableinterlocking means adjacent opposite ends for rigidly securing the firedamper frame in folded condition. The blank, in unfolded form, has amain planar central web portion disposed between parallel,longitudinally extending side peripheral mounting regions ofsubstantially double blank thickness,'and a pair of longitudinallyextending, spaced, parallel upstanding flanges disposed at substantiallyright angles from an inner surface of the main planar central webportion and terminating at longitudinally extending outer edges. Eachflange includes longitudinally spaced relief regions defining separateflange sections, each relief region in one flange being in transversealignment with a corresponding region in the other flange. Each reliefregion comprises a slit extending from the outer edge of its respectiveflange in an inward direction for substantially the entire outwardextent of the flange, and a portion of at least one of the flangesections adjacent each slit is disposed transverselyvout of the generalplane of the longitudinally extending flange. Adjacent flange sectionsof each respective flange overlap to form frame corners when the frameis folded through the relief regions transverse to the elongatedimension of theblank to form a substantially continuous peripherallyvextending channel.

2 Claims 8 Drawing Figures 1 PMENTEUnm 30 ms t 3.768; 223

' SHEET 1 UF 2 INVENTOR.

JOHN C. KURZ I J26 SV xm/a ATTORNEY.

PAIENIE nnm 30 ms .iEET 2 BF 2 INVENTOR JOHN 'C. KURZ ATTORNEY.

BACKGROUNOOF THE INVENTION 1. Field of the Invention This inventionrelates generally to fire damper structures and more particularlyrelates to a unique one piece fire damper frame in which a stack'ofreversely folded, interlocking blades is mounted to define a curtain forclosing acentral opening defined by the fire damper frame; v

2. 'Des cription'of the Prior Art 7 Fire damper frames of'one piececonstruction are known in the 'prior art, as exemplified by U. S. Pat.No. 3,327,766. These frames are .adapted for installation in airdelivery systems, such as duct structures, and define a centrally opentransverse cross section which is automatically closed bya plurality ofhingedly interfitted metal blades uponioccurrence of elevatedtemperatures .within the duct. Fire dampers normally are employed asfire barriers within air ducts extending into adjacent fire separatedareas and are required to close these air ducts in the event of a fireto prevent the fire from spreading into adjacent fire separations.Therefore, fire dampers must form a substantially air tight system toprevent the spread of fire, and must meet rigid specifications definedin appropriate Underwriters Laboratoriespublications and other similarstandards.

The one piece fire damper frame disclosed in US. Pat. No..3,327,766, isforr'nedfrom alongitudinally extending blank having a central webdisposed between transversely spaced, upstanding flanges, and a pair ofperipheral mounting regions. The upstanding flanges are of substantiallydouble blank thickness, and have. longitudinallyspaced V-shaped notchesformed therein to form reliefregions through which the blank is foldedinto its closed frame construction. Opposite ends of the longitudinallyextending blank are provided with a plurality of transversely spaced,longitudinally extending fingers, The fingers at one end are disposed tointerdigitate with the transverse space between the fingers at the otherend so as to forman interlocking structure for maintaining the firedamper frame in its closed condition. In folded condition inclinededgesdefined by each V-shaped notch abut each other such that thetransversely spaced flanges, in conjunction with the central web, defineinwardly directed channels which cooperate with the interlocking bladesforming the curtain to close the opening defined by the fire damperframe in the event of a fire. The peripheral mounting regions are ofsingle blank thickness, and haveopenings therein to permit attachment ofthe fire damper frame within an air delivery system, such as a ductstructure.

The above described fire damper framehas several structuralinadequacies. The butted inclined edges defined at each V-shaped notchforms a frame corner which does not aidin providing transverse, orlateral support for the fire damper frame. Furthermore, theinterdigitated fingers which, form the locking means for retaining thefire damper frame in closed condition may become loosened and therebycause the frame to partially open and thereby fail to properly cooperatewith the interlocking blades of the curtain to form a substantially airtight structure in the event of fire. The longitudinally extendingperipheral mounting regions are of single stock thickness and are not ofan optimum rigid construction for attachment to the walls defining anair duct. In addition, the transversely spaced, upstanding flanges areof double stock thickness and are formed by an intricate foldingoperation which reduces the 'speed of manufacture of such fire damperframes, and thereby increased the cost 'of such manufacture.

I SUMMARY OF THE INVENTION The folded one piece fire damper frame ofthis invention has a centrally open transverse cross section formed froma longitudinally extending, unitary blank. The unitary blank,,inunfolded form, is'defined by a main planar central web portion disposedbetween transversely spaced apart longitudinally extending sideperipheral mounting regions of substantially double blank thickness, anda pair transversely spaced apart longitudinally extending parallelflanges of single stock thickness disposed inwardly of the sideperipheral mounting regions. Each flange extends outwardly at 'asubstantially right angle to an inner surface of the main planar webportion and terminates at a longitudinally extending outer edge.Longitu'dinally spaced apart relief regions are formed in each flange todefine separate flange sections, and each relief region in one flange isin substantial transverse alignment with a relief region in the otherflange todefine transverse fold lines about which the unitary blank isfolded to form the fire damper frame.- Each relief region is defined bya slit extending from the outer edge of its respective flange in aninward direction for substantially the entire outward extent of theflange. At least one of the flange sections adjacent each slit isdisposed transversely out of the general'plane of the longitudinallyextending flange so that adjacent flange sections will overlap to defineframe corners when the blank is folded into its fire damper frameconfiguration. The overlapping flange sections cooperate with the mainplanar central web portion to define a substantially continuousperipherally extending channel within the blank. One longitudinal end ofthe blank has transversely spaced fingers extending therefrom whichcooperate with slits at the opposite longitudinal end to form aninterlocking construction to maintain the fire damper frame in itsfolded condition. e

The peripheral mounting regions of double blank thickness are extremelyrigid, and can therefore be secured directly to the walls defining anair duct withoutany resulting distortion of the fire damper frame. Theoverlapping flange sections defining each frame corner add a high degreeof lateral stability to the fire damper frame, and assures that asubstantially continuous peripherally extending channel will bemaintained in the fire damper frame. In the prior art unitary firedamper frame disclosed in U. S. Pat. No. 3,327,766, any transversemisalignment between flange sections at a frame I corner caused adiscontinuity in the peripherally ex- It is therefore an object of thisinvention to'provide an improved folded, one piece fire damper framesubstantially as set forth above.

It is a further object of this invention to provide a folded, one piecefire damper frame having a rigid peripheral mounting region ofsubstantially double blank thickness.

It is a further object of this invention to provide a folded, one piecefire damper frame having interlocking means for preventing said firedamper frame from partially opening during use.

It is a further object of this invention to provide a folded, one piecefire damperframe having overlapping adjacent flange sections definingeach frame corner to enhance the lateral stability of said fire damperframe.

It is a further object of this invention to provide a folded, one piecefire damper frame which is inexpensive to manufacture, and reliable inoperation.

Other objects and a fuller understanding of the invention will be had byreferring to the following description and claims of the preferredembodiment thereof, taken in conjunction with the accompanying drawingswherein like reference characters refer tosimilar parts throughout theseveral views and in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometric view of a firedamper employing a folded one piece fire damper frame according to thisinvention.

FIG. 2 is a fragmentary, isometric view showing details of a cornerconstruction of the folded, one piece fire damper frame shown in FIG. 1.

FIG. 3 is a fragmentary, isometric view of a modified cornerconstruction of a folded, one piece fire damper frame according to thisinvention. I

FIG. 4 is an isometric view of a unitary blank from which the folded,one piece fire damper frame of FIG. 1 is constructed.

FIG. 5 is an isometric view of a unitary blank from which the folded,one piece fire damper frame having the modified corner constructionshown in FIG. 3 is formed.

FIG. 6 is an isometric view of a unitary blank showing a modifiedlocking arrangement for maintaining the fire damper frames according tothis invention in folded condition.

FIG. 7 is a partial, isometric view of a unitary blank showing a secondmodified fire damper frame corner construction.

FIG. 8 is a partial, elevational view of the unitary blank of FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION Althoughspecific terms are used in the following description for the sake ofclarity, these terms are intendedto refer only to the particularstructures of my invention selected for illustration in-the drawings,and are not intended to define orlimit the scope of the invention.

Referring to FIG. 1, a fire damper unit 10 employing a folded, one piecefire damper frame 12 of this invention is shown. The fire damper frame12 is adapted to be secured in air delivery systems, such as ductstructures, and has a centrally open transverse cross section 13. Ablade or slat assembly 14 is comprised of a stack reversely folded,continuous, interlocked blades which define a curtain for closing theopen area 13 in the event of fire. The interlocked blades forming theblade assembly 14 do not form a part of the present invention, butpreferably are of the type disclosed in U. S. Pat. No. 3,273,632, thesubject of which is hereby incorporated by reference. A fusible link 16is disposed in underlying relationship with the lower-most blade of theblade assembly 14, and is fixedly secured to a pair of cinch straps 18(only one of which is shown in FIG. 1). The fusible link 16 is comprisedof a low temperature fuse metal which melts when exposed to temperaturesencountered when a fire occurs to thereby permit the blade assembly 14to open by gravity or otherwise to close the open area 13. If desired,positive acting spring means can be securedto the blade assembly 14 topositively close the blade assembly to close the open area 13. Thislatter mentioned construction is particularly desirable when'the firedamper unit 10 is disposed in a horizontal plane within a ductstructure.

Referring now 'to FIGS. 1, 2, and 4, a fire damper frame 12 according tothis invention will now be described. The fire damper frame 12 is formedfrom a longitudinally extending, unitary sheet metal blank 20. The blank20 has a main planar central web portion 22 disposed between a pair oftransversely spaced, longitudinally extending side peripheral mountingregions 24 and a pair of transversely spaced, longitudinally extendingparallel upstanding flanges 26. The peripheral mounting regions 24 areof substantially double blank thickness and are formed by folding sideregions of the sheet metal stock through substantially along elongatefold lines 28 and 30 respectively. A plurality of mounting holes 32 areformed in the peripheral mounting regions 24 to permit attachment of thefire damper frame 12 to the walls defining air delivery systems, such asduct structures. Marginal sections of the folded side regions areprovided with a reverse bend of substantially ninety degrees alongelongate fold lines 34 and 36, respectively, to define the upstandingflanges 26. The upstanding flanges terminate in longitudinally extendingouter edges 37.

One longitudinal end of the metal blank 20 is provided with a pluralityof transversely spaced fingers 38 which are formed by any suitableoperation such as punching or die cutting, and the outer fingers extendat least partially in longitudinal alignment with the peripheralmounting regions 24. The opposite longitudinal end of the metal blank 20is provided with a pair of tab extensions 40, 42. Elongate transverseslits 44 are formed at the junction of the tab extensions 40 and 42 withthemain planar central web portion 22. The slits 44 are in longitudinalalignment with the fingers 38, whereby the fingers will be disposedwithin the slits when the unitary sheet metal blank 20 is folded to formthe fire damper frame 12, as shown in FIG. 1.

Referring to FIG. 4, each upstanding flange 26 is provided withlongitudinally spaced, identical, relief regions 50 defined by a slit ordie cut 52 which separates each upstanding flange 26 into separateflange sections 54. Each relief region 50 in one of the upstandingflanges 26 is in transverse alignment with a relief region 50 in theother flange 26 to define transverse fold regions along which theunitary sheet metal blank 20 is folded to form the fire damper frame 12.Each flange section 54 has a body region 55, and a lance region 56 whichis disposed out of the general plane of the body region 55. Each lanceregion 56 is disposed adjacent a body region 55 of an adjacent flangesection 54 to permit overlapping of adjacent flange sections when thesheet metal blank 20 is bent through the relief regions to form thedesired fire damper frame (FIG. 2). End margins 58 and 60 of each flange26 are not provided 'with lance regions, but are sufficiently flexibleto be adjacent each die cut are curved out of the general plane of theinitially formed continuous flange, as indicated at 62, in oppositedirections from the elongate .center linev of the undeformed continuousflange,

whereby adjacent flange sections overlap as shown in FIG. 3 to definethe frame corners of a formed fire damper frame 12.

Referring to FIG. 6, a modified locking arrangement is shown formaintaining a formed fire damper frame in its formed condition. Theinterlocking structure shown in FIG. 6 includes two transversely spacedfingers 38b at one longitudinal end of the sheet metal blank and asingle tab 40b at the opposite longitudinal end of said sheet metalblank. Transversely spaced elongate slits 44b are formed at the junctionbetween the tab extensions 40b'and the main planar central web portion22 to cooperate with the transversely spaced fingers 38b in retainingthe fire damper frame 12 in its formed condition. The fingers 38b aredisposed through the elongate slits 44b and are then bent atsubstantially a 90 angle to overlie the outer exposed surface of thefire damper frame 12 in the manner shown in FIG. 1. The lockingarrangement shown in FIG. 6 can be utilized with either a unitary sheetmetal blank having relief regions 50 as shown in FIG. 4, or reliefregions 50a asshown in FIG. 5.

The overlapping flange sections in the fire damper frames ofthisinvention define frame corners which add lateral rigidity to saidfire damper frames, and which provide substantially continuousperipherally extending channels for cooperatingwith the blade assembly14 to adequately assure that a substantially air tight system is createdin the event of fire. The peripheral mounting regions 24 of doublethickness are extremely rigid and provide reliable means through whichthe fire damper frame 12 can be secured to the walls of a suitable ductstructure without distorting said fire damper frame. The uniquecooperation between the fingers at one end of the sheet metal blank andthe elongate slits at the opposite end of said blank provides positiveassurance that the fire damper frame will not open, even if the fingerstend to bend out of engagement with the outer exposed surface of saidfire damper frame.

Referring now to FIGS. 7 and 8, I show a second modified unitary sheetmetal blank 20b-The blank 20b differs from the sheet metal blank 20 inthe specific construction of the V-shaped notches 52b. The V- shapednotches 52b cut entirely through the initially formed, continuousflanges to define adjacent flange sections 54b. The portions of theflange sections 5411 immediately adjacent each V-shaped notch 52b bendrespectively alternately slightly inwardly and outwardly from thegeneral plane of the initially formed continuous flange, wherebyadjacent flange sections overlap in the manner illustrated in FIG. 3 todefine the frame corners of a formed fire damper frame 12.

I claim:

1. In a folded, one piece fire damper frame having a centrally opentransverse cross section formed from a longitudinallyextending unitarysheet metal blank, the combination of A. a longitudinally extending,planar, central web portion,

1. said web portion being of single blank thickness;

B. a pair of transversely spaced, longitudinally extending, peripheralmounting regions,

I. said blank being longitudinally bent to define the mounting regions,

2. said mounting regions being of double blank thickness to provideincreased peripheral strength for fire damper mounting purposes;

C. a pair of transversely spaced, longitudinally extending, parallelflanges disposed inwardly of the side peripheral mounting regions,

1. a plane through said flanges extending at right angles to a planedrawn through the web portion,

2. said flanges being formed of single blank thickness;

D. a plurality of longitudinally spaced relief regions formed in eachflange,

I. each relief region in one flange being in transverse alignment with arelief region in the other flange,

2. each relief region comprising a slit extending the entire height ofthe flange to define adjacent right and left flange sections,

3. at least one of the right and left flange sections adjacent each slitbeing curved out of the general plane drawn through the flange to formright or left curved regions,

4. each right curved region curving in a first direction from the planethrough the flange and each left curved region curving in seconddirection from the said plane, said second direction being opposite thefirst direction,

5. the said frame being folded through the relief regions transverselyto the length of the blank to form frame corners.

2. The invention of claim 1 wherein the right and left curved regionscurve away from the said plane a distance' sufficient to permit therespective right and left curved regions to overlap when the frame isfolded through the relief regions.

1. In a folded, one piece fire damper frame having a centrally opentransverse cross section formed from a longitudinally extending unitarysheet metal blank, the combination of A. a longitudinally extending,planar, central web portion,
 1. said web portion being of single blankthickness; B. a pair of transversely spaced, longitudinally extending,peripheraL mounting regions,
 1. said blank being longitudinally bent todefine the mounting regions,
 2. said mounting regions being of doubleblank thickness to provide increased peripheral strength for fire dampermounting purposes; C. a pair of transversely spaced, longitudinallyextending, parallel flanges disposed inwardly of the side peripheralmounting regions,
 1. a plane through said flanges extending at rightangles to a plane drawn through the web portion,
 2. said flanges beingformed of single blank thickness; D. a plurality of longitudinallyspaced relief regions formed in each flange,
 1. each relief region inone flange being in transverse alignment with a relief region in theother flange,
 2. each relief region comprising a slit extending theentire height of the flange to define adjacent right and left flangesections,
 3. at least one of the right and left flange sections adjacenteach slit being curved out of the general plane drawn through the flangeto form right or left curved regions,
 4. each right curved regioncurving in a first direction from the plane through the flange and eachleft curved region curving in second direction from the said plane, saidsecond direction being opposite the first direction,
 5. the said framebeing folded through the relief regions transversely to the length ofthe blank to form frame corners.
 2. The invention of claim 1 wherein theright and left curved regions curve away from the said plane a distancesufficient to permit the respective right and left curved regions tooverlap when the frame is folded through the relief regions.
 2. saidmounting regions being of double blank thickness to provide increasedperipheral strength for fire damper mounting purposes; C. a pair oftransversely spaced, longitudinally extending, parallel flanges disposedinwardly of the side peripheral mounting regions,
 2. said flanges beingformed of single blank thickness; D. a plurality of longitudinallyspaced relief regions formed in each flange,
 2. each relief regioncomprising a slit extending the entire height of the flange to defineadjacent right and left flange sections,
 3. at least one of the rightand left flange sections adjacent each slit being curved out of thegeneral plane drawn through the flange to form right or left curvedregions,
 4. each right curved region curving in a first direction fromthe plane through the flange and each left curved region curving insecond direction from the said plane, said second direction beingopposite the first direction,
 5. the said frame being folded through therelief regions transversely to the length of the blank to form framecorners.